Display rotate manipulator controls?
Just enable the 'Transform Manipulator' in the 3D header:



Ctrl+Space will toggle the Transform Manipulator on or off. You can also Shift select the options beside the Transform Manipulator option to show the Location, Rotation and Scale controls at the same time.

For blender 2.8 the manipulator section is on the toolbox on left of the screen (if you can't see it press T)